Li, who started the day in joint second place with South Africa's Zander Lombard, got off to a wonderful start, chipping in an eagle from the rough on the very first hole.
The 23-year-old, who said he had a lot of luck, birdied the par-five fourth but got in trouble soon after with a double bogey on the sixth hole before steadying the ship by sinking an 18-footer for another birdie on the seventh to turn in 33.
Li made another eagle immediately after the turn followed by a series of pars before closing his round with back-to-back eagles on the par-four 17th and par-five 18th to draw level with Johnson in King Abdullah Economic City.
"Very lucky today," Li said. "Those eagles, especially the last couple of shots, were really solid but except (for) that, honestly, my play, wasn't that good.
"If (the approach into the first) didn't go in the hole, it could have been off the green. It's a very lucky eagle over there. At the 10th, that's what I wanted to play, but I felt like I pushed it a little bit.
"I got a lucky bounce, kicked it left and it went in the hole, which is very lucky, too."
Johnson made birdies on the second and fourth holes, before dropping his only shot of the day on the fifth.
He closed out his front nine with a birdie to turn in 33 and gained three more strokes with three birdies in a row from the 10th before ending his round with a series of pars.
"I thought I played well. I probably played just as well as I did yesterday," he said. "I gave myself a lot of opportunities and made a lot of good putts. Just holed a few more yesterday than I did today, is the only difference.
"Haotong is a good player. He's obviously playing well right now. I think it's going to be kind of a tough match against him tomorrow for the most part, but I'm looking forward to it."
Former U.S. Masters champion Sergio Garcia was disqualified earlier in the day for intentionally damaging the greens at the Royal Greens Golf and Country Club.
(Reporting by Simon Jennings in Bengaluru; Editing by Ken Ferris)
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